Gun perforator



J. O- TOW GUN PERFORATOR 4 Filed Sept. 9. 1946 ill],

Nqv. 21, 1950 INVENTOR JAMES o. TOW

ATTORNEY Patented Nov. 21, 1950 UNITED STATES PATENT OFFlQ GUN PERFORATOR Application September 9, 1946, Serial No. 695,768

6 Claims.

My invention relates to guns for perforating well casing by firing projectiles therethrough so as to produce openings in. the casing through which fluids may flow from theform'a-tion. into the interior of the casing, and relates in particular to a novel. method-and apparatus for firing the propellant charges of well casing perforating guns.

Itis an'object of the invention to produce a simplification in well perforating guns and means for'flring the propellant charges thereof- The present invention avoidsthe use of electrical firing means and the dangers involved .in the use thereof, and also avoids the useoffiring passages of the type now extensively employed in gun bodies, these passages. leading from a chamber which receives a firing charge or primer. to the casing whereby, the propellant charge disposed.

behind the projectile is ignited by heat which is produced, externally of the propellant receiving chamber, and which heat is conducted through a wall of the propellant. receiving chamber such heat being of such temperature that it will cause ignition of the propellant charge. Herein the term propellant charge includes not only the main body or massof powder, but also any temperature responsive combustible substance which may be incorporated in the propellant charge, responsive toheat for ignition. In the ordinary practice of the invention'the propellant charge may consist simply of a mass of powder, but a fuse element, heat responsive primer or other substance may be employed in the propellant charge.

It is a further object of the invention to provide a method and apparatusin which heat produced in or delivered into a cavity is conducted through a metal wall to the propellant charge which is disposed in the propellant. receiving chamber of 'agun body formed so that'it may be lowered into a well.

A further object of the'invention is'to provide amethod and apparatus-wherein molten metal isdelivered to a cavity in. the gun body, and heat.

from this molten metal is conducted through a metal wall to the propellant charge.

A further object of the invention is to provide amethod and apparatus wherein-a chemical reaction of heat'producing nature'is performed in a cavity inthe well. perforating gun. body, heat from this chemical. reaction being conducted through a. metal wallof .thegun'body'to the pro-,

pellant or to a fuse or primer associated with the propellant.

A further object of the invention is to provide a method and apparatus wherein a chambered go-devil, having therein a heated or heat producing substance, is passed down through a string of tubing to a gun connected to its lower end, and the substance is released from the godevil so that as the result thereof, heatwill be conducted through a metal wall of the gun body to a mass of propellant powder disposed behind a projectile, or to an ignition, priming, or fuse means associated therewith.

Further objects and advantages of the invention may be brought out in the following part of the specification, wherein specific description is for the purpose of fully disclosing three forms of the invention without limiting the scope of the invention set forth in the appended claims.

Referring to the drawings which are for illustrative purposes only,

Fig. 1 is a fragmentary sectional view show.- ing a preferred embodiment of my invention.

Fig. 2 is an enlarged sectional View taken as indicated by the line 22 of Fig. 1.

Fig. 3 is a fragmentary sectional view showing an alternative placement of the heater tube or cavity.

Fig. 4 is a sectional view similar to Fig. 2, but showing. the manner in which the heater tubes or cavities of the gun body may be employed Without heat conducting inserts.

In Fig. 1 I have shown gun body I I made from a cylindric bar of steel by machining or boring the necessary openings or cavities therein. The

simplicity of form of the gun body contributes to its economical and relatively fast manufacture.

The upper end of the gun body l I has a recess I2. provided with an internally threaded counterbore I3 whereby the'gun body I I may be connected to the lower end of a string of tubin M by whichof illustration only, the bores I5, indicated respectively by the numerals I5, 550., I51), and I50, are

disposed in vertical planes which cross at an angle of substantially It will be understood that other desired angular relations of the gun bores lfimay be employed.

Atrthe inner end of the gun bores I5, there are" In the arrangement of bores I5, which I have shown in Fig. 1 for the purpose.

propellant receiving chambers 16 which are axially aligned with the gun bores I5, and being of slightly reduced diameter, provide shoulders I! which define the line of division between each propellant receiving chamber 16 and its associated bore l5, and against which shoulders I! the inner ends of projectiles I8 may rest. The outer ends of the bores are sealed by rubber plugs 30.

As shown in Fig. 2, longitudinal holes 20, 20a, 20b, and 266 are drilled inward from the bottom end of the body H and the upper ends of these openings 20 communicate with the recess l2, as shown in Fig. l. The openings 20, 20a, 20b, and 23c are respectively placed adjacent and offset from the propellant receiving chambers it of the bores I5, [5a, b, and I50. These openings 20, a, 23b, and 290 form heater tubes or cavities associated with the respective propellant receiving chambers l6, and as best shown in Fig. 2, a hole 2| is drilled laterally into the gun body l i so as to extend the cavity 20 into a position behind the chamber IS with which the cavity 20 is operatively associated. Also, the rear end of each chamber 26 is provided with an insert 22 having a cylindric body portion 23 and a stem 24 which projects through an intercornmunicatin opening 25 from the inner end of the chamber l6 into the laterally directed portion 2| of the heater tube or cavity 20.

In each of the inserts 22 an opening 25 is extended from communication with the chamber l6 into the stem 24. I'his opening 26 may be filled with powder 21 of the same type as employed in the propellant charge 28, which is placed in the propellant receiving chamber [6. Or the powder 2! may be of a type which will ignite at a lower temperature than the powder employed in the propellant charge 28. The opening 26 in the insert 22 constitutes an extension of the chamber l6, and the powder 21, regardless of its character, constitutes a portion of the propellant charge 28.

In Fig. l I show a chambered go-devil 33 in the tubing [4, in a position near the lower end of the tubing [3. This go-devil 30 comprises a vertically elongated shell 3| with an internal layer of insulation 32. In the lower end of the go-devil 30 there is an opening 33 having valve seat 34 at its inner end to receive a closure shown as a ball 35. At the upper end of the go-devil shell 3! there is a vent opening 33. At the top of the well, the chamber 37 of the go-devil 30 is filled with a heated substance which, when it is delivered into the cavities 20, 20a, 20b, and 200, will transmit high temperature heat through the heat conducting wall of the insert 22 and cause ignition of the propellant charge 28. For example, the chamber 31 of the go-devil 30 may be filled with .a, hot liquid metal at a temperature at least as high as the the ball from the seat 34, permitting the content of the chamber 3'! to flow down through the openings and the recess l2 into the heater cavities 20, 20a, 20b, and 200 to transmit heat to the heat conducting wall of the inserts for the purpose of firing the charges therein, and propellant charges 28.

The invention also comprehends the use of substances which, when combined in the cavities 20, 28a, 20b, and 20c, will produce heat of a temperature suifioiently high to produce ignition of the propellant charges 28 as a result of conduction of such heat through at least a portion of the external walls of the propellant receiving chambers l6. For example, the cavities 20, 20a, 20b, and 200 may be filled with a slow burning powder and the chamber 31 of the go-devil 30 may have therein a chemical which, when brought into contact with the slow burning powder, will cause the same to burn, thereby producing in the cavities 20, 29a, 23b, and 200, the desired heat and temperature for producing ignition of the propellant charges. Chemical reaction, other than combustion, may be employed in the cavities to produce the heat required for the ignition of the propellant charges 28.

In Fig. 3 I have shown how a heater tube or cavity 20 may be disposed directly behind a propellant receiving chamber l6, so that it will not be necessary to employ the lateral extensions 2| of the heater cavities shown in Fig. 2. When this arrangement is employed, an insert 22 of heat conducting metal may be disposed so that its stem 24 will project through an opening 25 which directly connects the rear end of the chamber IS with the cavity 28.

In Fig. 4 I have shown a gun body ll having therein heater tubes 40, respectively indicated by the numerals 4D, Mia, 40b and 400, into which a heated substance may be introduced or in which heat may be created to accomplish firing of one or more propellant charges without employing inserts such as shown at 22 in Figs. 1, 2, and 3.

In Fig. 4 I have shown a single gun bore IE, but it will be understood that in the gun body I I other gun bores may be placed in vertically temperature of ignition of the powder 21 in the inserts 22. This hot liquid metal may be mercury or it may be any other metal or alloy which will melt at a relatively low temperature. Herein I have employed the term molten metal with reference to the substance delivered into the cavities 20, 20a, 23b, and 290, and desire to have it understood that this terminology applies to mercury.

For release of the substance from the chamber 31 of the go-devil 30, I provide at the upper end of the gun body II a bushing 39 having openings 40 which communicate with the recess l2 and a post 4| which, when the go-devil 33 moves downward from the position in which it is shown in Fig. 1, passes through the opening 33 and raises spaced relation and pointing different directions. At the inner end of the bore I5 there is a propellant receiving chamber I6 which is disposed adjacent the cavity 40' and is separated from this cavity 48' by a metal wall 42. In the operation of this form of the invention a propellant, such as a mass of powder 28', is placed in the chamber IS, a projectile I8 is placed in the bore I5 and the bore I5 is sealed by means of a rubber plug 30'. Heat applied to or produced in the cavity 40 heats the wall 42 and, accordingly, heat is conducted through this wall 42 to the powder 28 in the chamber IE to cause this powder 28' to burn, whereupon its explosive action will drive the projectile l8 out of the bore I5 and through the wall of the casing to be perforated.

I claim as my invention:

1. In a well perforating gun, the combination of: a gun body adapted to be lowered into a well, said body having a bore to receive a projectile and wall means forming a chamber at the rear end of the projectile to receive a propellant comprising an explosive and ignitable composition, said gun body having a cavity adjacent at least a part of said wall means and externally of said chamber; and means for introducing molten metal into said cavity so that heat therefrom will be conducted through said wall means to cause ignition of said propellant.

2. In a well perforatin gun, the combination of: a gun body adapted to be lowered into a well, said body having a bore to receive a projectile and wall means forming a chamber at the rear end of the projectile to receive a propellant comprising an explosive and ignitable composition; and means for conducting a mass of heated substance into proximity to at least a part of said wall means externally of said chamber, whereby the conduction of heat therethrough will cause firing of said propellant.

3. In a well perforating gun, the combination of: a gun body adapted to be lowered into a well, said body having a bore to receive a projectile and wall means forming a chamber at the rear end of the projectile to receive a propellant comprising an explosive and ignitable composition, said gun body having a cavity adjacent at least a part of said wall means and externally of said chamber, said cavity having a portion which communicates with the upper end of said gun body; means for connecting the upper end of said gun body to the lower end of a strin of tubing: a chambered go-devil adapted to be passed down through said tubing, said go-devil having therein a substance which will, at least in part, enter into the effect of producing heat; and means at the lower end of said tubing for releasingsaid substance from said go-devil.

4. In a method of firing a well perforating gun device comprising a body adapted to be lowered into the well which is to be perforated, said body having a gun bore, a propellant receiving chamber at the inner end of said bore, and a cavity in said body separated from said chamber by a heat conducting wall, the steps of: placing a propellant and a projectile respectively in said chamber and. said bore; and deliverin a heated substance into said cavity so that heat will be con ducted through said wall to cause the firing of said propellant.

5. In a method of firing a well perforating gun device comprising a body adapted to be lowered into the well which is to be perforated, said body having a gun bore, a propellant receiving chamber at the inner end of said bore, and a cavity in said body separated from said chamber by a heat conducting wall, the steps of: placing a propellant and a projectile respectively in said chamber and said bore; and delivering molten metal into said cavity so that heat will be conducted through said wall to cause the firing of said propellant.

6. In a method of firing a well perforating gun device comprising a body adapted to be lowered into the well which is to be perforated, said body havin a gun bore and a propellant receiving chamber at the inner end of said bore, said chamber having a heat conducting external wall, the steps of: placing a propellant and a projectile respectively in said chamber and said bore; and applying molten metal to the outer face of said wall so that heat will be conducted through said wall to cause the firing of said propellant.

JAMES O. TOW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,201,290 Greene May 21, 1940 2,257,276 Reynolds Sept. 30, 1941 2,351,179 Aloi June 13, 1944 2,414,900 Schiavon Jan. 28, 1947 2,418,486 Smylie Apr. 8, 1947 

